TCP/IP

A survival guide

What is TCP/IP

• Transmission Control Protocol / Internet Protocol

• TCP/IP is the data protocol used by all internet applications (email, www, file download, etc)

• Used by VikinX Modular routers and panels, Gyda, THOR and ETH-CON

Ethernet

• Ethernet is a physical data communication interface

• Used for in-house (LAN) networks and short, medium and long haul applications (e.g. flashlink ETH100)

TCP/IP on Ethernet

• TCP/IP is a data protocol, not a physical interface

• TCP/IP is designed to be used on many data carriers like Ethernet, ATM, ISDN, and ADSL/SDSL

• Data can travel between different networks using one unified protocol: TCP/IP

Example

Example #1

• Source IP: 192.168.1.22• Destination IP: 201.2.235.56• Net mask: 255.255.255.0• Source Network Address: 192.168.1.0• Destination Network Address: 201.2.235.0• Destination is on another net, send data to the

Default Gateway

Example #2

• Source IP: 192.168.1.22• Destination IP: 192.168.1.133• Net mask: 255.255.255.0• Source Network Address: 192.168.1.0• Destination Network Address: 192.168.1.0• Source and destination is on the same net,

send data directly (Not to the Default Gateway)

IP Addresses

• An IP address is like a computer phone number

• Every node on an IP network has a unique IP address, and the address is used to distinguish between different computers (nodes on the network)

• An IP address consists of 4 numbers separated with dots (e.g. 192.168.1.33)

• You can’t connect to a remote node without knowing its IP address

Routing Basics

• Ethernet is a “broadcast protocol”, all data is broadcast to all nodes on the network all the time

• TCP/IP is a routed protocol. Data is sent from node to node from the source to the destination, enabling TCP/IP to be used on very big networks (e.g. The Internet)

Default Gateway

• The Default Gateway is usually an IP router with one or more connections to the Internet or the corporate network

• Often the default gateway is connected to “the rest of the world” through some other media than Ethernet (e.g. ADSL, ISDN, T1, ATM, etc)

• The Default Gateway has an IP address

Use of the default gateway

• All local computers (computers on your own Ethernet) can be reached directly, and data is not sent via the default gateway

• Data sent to any other computer is sent to the default gateway, and the gateway will take care of sending the data to the final destination

The Subnet Mask

• The Subnet Mask (Net mask for short) filters out which data stays on your network and which needs to be sent to the Default Gateway

• The mask consists of 4 numbers separated by dots (e.g. 255.255.255.0)

• The mask splits the address space in two, one local and one non-local

Network Address

• The Network Address is the common address for all computers on a local network

• The Net mask is used together with the IP address to create the Network Address

• If the destination Network Address is different to the local Network Address, then the data is sent to the Default Gateway

• All nodes on your local network will have the same Network Address

• The IP address is combined with the Net mask to create the Network Address

• Net mask = 255, copy IP to the Network Address• Net mask = 0, zero the Network Address(The Net mask can have other values (advanced))

Network Address Calculation

01168192Network Address

0255255255Net Mask

331168192IP Address

DNS

• The Domain Name Service (DNS) is the “phone book” of the internet and converts between domain names (e.g. www.network-electronics.com) and IP addresses (195.1.135.56)

• The domain names are easier to remember than IP addresses

Microsoft Windows XP

Linux IP Configuration